.wrapper {
  position: fixed;
  top: 0;
  display: flex;
  flex-flow: column;
  align-content: stretch;
}

header {
  z-index: 990;
  display: flex;
  height: 6vh;
  align-items: center;
  background: #FDFDFD;
}

header>img {
  padding-left: 5vw;
  height: 1.3rem;
}

#title {
  flex-grow: 1;
  text-align: center;
}

#title .ico {
  width: 1.1rem;
  vertical-align: top;
  margin: 0 .5em;
}

#title .k {
  font-size: 1rem;
  font-weight: bold;
  vertical-align: top;
}

.outlink {
  font-size: .8rem;
  color: #EA3F34;
}

nav {
  width: 100vw;
  z-index: 999;
  display: flex;
  justify-content: space-around;
  background-color: #FDFDFD;
  min-height: 6vh;
  border-top: 1px #D7D7D7 solid;
}

nav button {
  margin: 0;
  width: 30vw;
  font-size: 1rem;
  text-align: center;
  color: #586369;
  background: #FDFDFD;
  border: 0;
}

nav .act {
  color: #3899F5;
  border: 0;
  border-bottom: 3px solid #3899F5;
}

article {
  /* 撑起上部，否则会被遮盖 */
  margin-top: 12vh;
  overflow: scroll;
}

/*吸顶*/
.totop {
  margin-top: 6vh;
}